This project is designed to study the effect of vestibulo-toxic aminoglycoside antibiotics on the dynamics of the human vestibulo-ocular and vestibulo-spinal reflex systems, and to study adaptive properties of these reflexes following total loss of vestibular function. These studies will be performed in patients receiving aminoglycoside antibiotics by testing them with various combinations of oculo-motor pursuit, optokinetic and rotational vestibular stimuli. Upright postural control will be studied by manipulation of visual and ankle joint proprioception in patients with aminoglycoside induced vestibular ototoxicity. The Principal and Co-Investigators bring expertise from neuro-otology and bio-engineering, respectively, to this project. The results of this study should significantly advance the health care of patients receiving ototoxic antibiotics by providing sensitive quantitative methods for early detection of vestibular aminoglycoside ototoxicity, provide incidence figures for six commonly used aminoglycoside antibiotics, and provide information about adaptive motor reflex mechanisms in the individual patient which will be of value in designing rehabilitative treatment protocols.